This invention relates to mortar compounding apparatus, and more particularly to a control device of mortar compounding apparatus capable of providing an optimum mixing ratio of the constituents of motor, i.e., water, cement, sand supplied to a mixing tank.
Mortar is generally applied not only to the outer walls of buildings, but also to the inner walls of tunnels as well as cliffs so that it is necessary to bond the mortar to such surfaces with a strong bonding force. Accordingly, it is necessary to assure an optimum mixing ratio of the ingredients. When blasting mortar against the surfaces to be finished, the weight or volume of the respective ingredients is measured and then the measured ingredients are mixed together by a mixer.
However, such batch system in which measuring and compounding of the ingredients are repeated for respective batches is not suitable for buildings or civil works which require a large amount of mortar. Thus, the batch system not only greatly decreases the efficiency of the construction work but also requires a large labor and time.
To eliminate these disadvantages it has been proposed a continuous system wherein the weights of the ingredients such as cement, sand and aggregate are weighed while they are conveyed by a conveyor and the amount of water supplied to the mixer is controlled in accordance with measured weights. However, under a certain circumstance it is necessary to convey the mortar through a long pipe to a place at which the mortar is blown. In another case, it is impossible to use a conveyor. For this reason, the continuous system is not applicable to such applications. Further, in order to prepare mortar of high quality it is necessary to take into consideration not only the weights of the cement, aggregate and sand but also such other factors as the grain size of the aggregate and sand and the property of the cement. Thus, it is impossible to prepare high quality mortar with the continuous system described above in which the quantity of water is determined in accordance with the weights of the solid ingredients.
When water, aggregate, sand and cement are mixed together by a mixer, the force acting upon the blades of the mixer varies depending upon the ratio of mixing of these ingredients.
We have found that there is a definite relation between the force acting upon the blades of a mixer and the desired properties of the mortar, that is the strength and the rebound or splash of the applied mortar, and according to this invention, the force acting upon the blades is used to control the mixing ratio of the ingredients of mortar.